Use of a microjet reactor for the production of initiating explosive

ABSTRACT

What is described is the use of a microjet reactor for the production of initiating explosive, each of the starting solutions for explosive production in the microjet reactor being injected through a nozzle onto a common collision point into a reactor space enclosed by a reactor housing, a gas being admitted into the reactor space via an opening, and the resulting initiating explosive crystals being removed from the reactor housing together with the liquid and excess gas through a further opening.

This invention relates to the use of a microjet reactor for the production of initiating explosive.

Many initiating explosives are produced by mixing at least two starting solutions and precipitating the explosive in crystalline form from this mixture. Through the selection of the reaction parameters (temperature, motion of the mixture), an attempt is made to obtain definite, reproducible crystal sizes in the precipitation. This is problematic, however, because it is difficult to control the temperature and the guidance of the motion of a precipitation bath on a large scale. Temperature gradients come into being within the precipitation vessel, and the crystallization is additionally affected by stirring motions. The liquid is often drained after a predetermined precipitation time and the crystalline material is filtered out and fractionated by screening. The possibilities for reproducibly obtaining a definite grain-size distribution with this precipitation method are very limited. As a rule, the grain-size distributions obtained lie in a range of up to two orders of magnitude.

For primers in the motor vehicle safety field, initiating primers or initiating explosives with very small and reproducible crystal dimensions (typical sizes of <30 μm) are needed so that good thermal coupling can be effected between the electrical heating resistances and the crystals. In other applications of initiating explosives it is also desirable that many small crystals be in contact with the igniting resistance in question.

It is an object of the invention to overcome the disadvantages of the existing art and to create a method for the production of initiating explosive that leads in particular to very small crystals (for example in the range of 0.5 to 30 μm, preferably 1 to 20 μm, particularly preferably 1 to 10 μm), the crystal size obtained being largely controllable through adjustment of the process parameters and the grain-size spectrum being adjustable to be narrow and well-defined.

This object is achieved through the use of a microjet reactor for the production of initiating explosive, each of the starting solutions for explosive production in the microjet reactor being injected through a nozzle onto a common collision point into a reactor space enclosed by a reactor housing, a gas being admitted into the reactor space via an opening, and the resulting initiating explosive crystals being removed from the reactor housing together with the liquid and excess gas through a further opening. A microjet reactor is described, for example, in WO 00/61275, reference being expressly made here to the entire content of the disclosure of this publication.

Surprisingly, it was found that when a microjet reactor is used for the production of initiating explosive, the initiating explosive can be won in a narrow, well-defined and adjustable grain-size spectrum. In particular, it is possible in this way to obtain a initiating explosive with crystal sizes between 0.5 to 30 μm.

The size of the explosive crystals generated in precipitation can be reproducibly controlled by varying the operating parameters. To this end, the diameters of the reactant-supplying nozzles, the pump pressure, the temperatures and concentrations of the starting solutions, and the quantity of auxiliary gas can be varied. The nozzle diameter is preferably 10 to 1000 μm, particularly preferably 50 to 500 μm, and most particularly preferably 50 to 100 μm. The total throughput is preferably 10 to 1000 mL/minute, particularly preferably 50 to 500 mL/minute.

The following initiating explosives can preferably be produced through the use according to the invention: potassium dinitrobenzofuroxanate, lead azide, lead picrate, lead trinitroresorcinate and cesium dinitrobenzofuroxanate.

A further advantage of the use according to the invention is that fractional (and hazardous) screening can be omitted because of the well-defined crystal size of the initiating explosive.

The subject of the invention will be explained in greater detail with reference to the following Example.

EXAMPLE 1 Production of Potassium Dinitrobenzofuroxanate in the Microjet Reactor

In a microjet reactor with a reactor space 2 mm in diameter and 50 mm long, via two nozzles with a nozzle diameter of 100 μm, a sodium dibenzofuroxanate solution with a temperature of 23° C. and a concentration of 20 g/L and a potassium nitrate solution with a temperature of 23° C. and a concentration of 30 g/L were brought together with a nozzle pressure of 100 bar at each nozzle. Air was used as transporting gas. After two minutes' reaction, approximately 1 L of reaction liquid containing approximately 5 g of finely divided potassium dinitrobenzofuroxanate was obtained. 

1. Use of a microjet reactor for the production of initiating explosive, each of the starting solutions for explosive production in the microjet reactor being injected through a nozzle onto a common collision point into a reactor space enclosed by a reactor housing, a gas being admitted into the reactor space via an opening, and the resulting initiating explosive crystals being removed from the reactor housing together with the liquid and excess gas through a further opening.
 2. The use according to claim 1, characterized in that the nozzle diameter is 10 to 1000 μm.
 3. The use according to claim 2, characterized in that the nozzle diameter is 50 to 100 μm.
 4. The use according to claim 1, characterized in that the total throughput is 10 to 1000 mL/minute.
 5. The use according to claim 4, characterized in that the total throughput is 50 to 500 mL/minute.
 6. The use according to claim 1, characterized in that the initiating explosive obtained is potassium dinitrobenzofuroxanate, lead azide, lead picrate, lead trinitroresorcinate or cesium dinitrobenzofuroxanate. 